The present invention relates generally to a surface effect vehicle, and more particularly, to a multiple unit surface effect vehicle in which multiple units are connected together to form a continuous pressurized air cushion.
Generally, surface effect ships are vehicles that ride on a pressurized cushion of air over water when pressurized air is forced into a chamber defined beneath the surface effect ships. Surface effect ships generally include rigid hulls connected by a deck and include stern and bow seals. The space thus formed by the rigid hulls, deck and seals is pressurized with air supplied from lift fans to form an air layer between the hull and above the surface of the water. The air layer is a pressurized air cushion. The surface effect ship is lifted above the surface of the water, generally maintaining a lower portion of the hulls in the water. Because of reduced friction, the surface effect ship is able to move quickly over the water.
Multiple surface effect ships may be connected together to form a sea train such that the ships move together, thus able to carry greater amounts of cargo. When multiple surface effect ships or surface effect units are connected, each surface effect unit includes a separated pressurized air cushion sealed by a stern seal and a bow seal. During pressurization, some air escapes from each of the stern seal and the bow seal, thus requiring more pressurized air to maintain the air cushions.
Further, while the multiple air cushions allow the surface effect ships to move quickly over the water, when connected, the air cushions of the surface effect ships are not able to communicate in a sealed manner with one another.
In addition, each surface effect vehicle or unit requires at least one fan for the unit, and thus numerous fans and numerous power sources need to be utilized to move the entire sea train.
As an alternative to connecting multiple surface effect ships, a single, large surface effect ship may be utilized in order to carry a greater amount of cargo and provide a single continuous air cushion. However, if the surface effect ship is too large, when waves are straddled, a gap is created in the middle of the air cushion between the side hulls. Further, riding over the wave crests creates openings in the front or rear of the large surface effect ship, requiring surging of the lift fans to compensate for the loss of air cushion. Running the lift fans at changing speeds is inefficient and requires the use of larger fans and motors.